We extend the concept of statistical symmetry as the invariance of a probability distribution under transformation to analyze binary sign time series data of price difference from the foreign exchange market. We model segments of the sign time series as Markov sequences and apply a local hypothesis test to evaluate the symmetries of independence and time reversion in different periods of the ma...

Errors in the perception of mean-reversion expectations can cause stockmarket crashes. This view was proposed by Fischer Black after the stockmarket crash of 1987. I discuss this concept and specify a stock-price model with mean-reversion in returns. Using daily data of the Dow Jones Industrial Average and the S&P500 index I show that mean-reversion in returns is a transient but recurring pheno...

This paper analyzes the mean reversion and unit root properties of general diffusion models and their discrete samples. In particular, we find that the Dickey-Fuller unit root test applied to discrete samples from a diffusion model becomes a test of no mean reversion rather than a unit root, or more generally, nonstationarity in the underlying diffusion. The unit root test has a well defined li...

When the cell wall of Bacillus subtilis is removed by lysozyme and the resultant protoplasts are plated on hypertonic soft agar medium, each protoplast forms an L colony. L bodies from such L colonies again plate as L-colony-forming units (CFU). However, if protoplasts or L bodies are "conditioned" by 1 h of incubation in 0.4% casein hydrolysate medium and then incubated in 25% gelatin medium f...

Phytochrome in Sinapis alba L. (white mustard) seedlings undergoes both decay and reversion after an exposure to red light. This is typical of other crucifers and of dicotyledons in general. In the presence of sodium azide, decay is inhibited, and reversion continues at about the same rate as in buffer alone. The reversion has been demonstrated both in cotyledon plus hypocotyl hook and in hypoc...

Resistance spreads rapidly in pathogen or pest populations exposed to biocides, such as fungicides and antibiotics, and in many cases new biocides are in short supply. How can resistance be reversed in order to prolong the effectiveness of available treatments? Some key parameters affecting reversion of resistance are well known, such as the fitness cost of resistance. However, the population b...